skeletonizing of leaves on vegetable plants and roses

Hi, we have looked for insects or slugs or anything else that might be cannibalizing our vegetable plants, and now our roses. But in spite of looking for culprits as early as midnight and as late as dawn, we don't see any insect or slug activity. We did use a mulch made up of our own green (vegetable) waste and leaves and grasses. The brown waste was an amalgamy of our lawn and garden waste(nondiseased) and that which the gardener brought in. The problem could the mulch but I'd like to know what why. What should I be looking for and what can stop the spread of this occurrence? It does not seem to affect the rose blooms, but our bell pepper plants are not yielding (could be because we used seeds from a store-bought pepper).
PS: We also have a small amount of wasp activity at our home.